Serum vibriocidal responses when second doses of oral cholera vaccine are delayed 6 months in Zambia

John Mwaba, Caroline Cleopatra Chisenga, Shaoming Xiao, Harriet Ng'ombe, Elena Banda, Patrick Shea, Chileshe Mabula-Bwalya, Katayi Mwila-Kazimbaya, Natasha Makabilo Laban, Peter Alabi, Masuzyo Chirwa-Chobe, Michelo Simuyandi, Jason Harris, Anita S. Iyer, Samuel Bosomprah, Paul Scalzo, Kelsey N. Murt, Malathi Ram, Geoffrey Kwenda, Mohammad AliDavid A. Sack, Roma Chilengi, Amanda K. Debes

Research output: Contribution to journalArticlepeer-review


Two-dose killed oral cholera vaccines (OCV) are currently being used widely to control cholera. The standard dose-interval for OCV is 2 weeks; however, during emergency use of the vaccine, it may be more appropriate to use the available doses to quickly give a single dose to more people and give a delayed second dose when more vaccine becomes available. This study is an open label, randomized, phase 2 clinical trial of the vibriocidal response induced by OCV, comparing the responses when the second dose was given either 2 weeks (standard dose interval) or 6 months (extended dose interval) after the first dose. Vaccine was administered to healthy participants > 1 year of age living in the Lukanga Swamps area of Zambia. Three age cohorts (<5 years, 5–14 years, and ≥ 15 years) were randomized to the either dose-interval. The primary outcome was the vibriocidal GMT 14 days after the second dose. 156 of 172 subjects enrolled in the study were included in this analysis. The Inaba vibriocidal titers were not significantly different 14 days post dose two for a standard dose-interval GMT: 45.6 (32–64.9), as compared to the GMT 47.6 (32.6–69.3), for the extended dose-interval, (p = 0.87). However, the Ogawa vibriocidal GMTs were significantly higher 14 days post dose two for the extended-dose interval at 87.6 (58.9–130.4) compared to the standard dose-interval group at 49.7 (34.1–72.3), p = 0.04. Vibriocidal seroconversion rates (a > 4-fold rise in vibriocidal titer) were not significantly different between dose-interval groups. This study demonstrated that vibriocidal titers 14 days after a second dose when given at an extended\ dose interval were similar to the standard dose-interval. The findings suggest that a flexible dosing schedule may be considered when epidemiologically appropriate. The trial was registered at Clinical (NCT03373669).

Original languageEnglish (US)
Pages (from-to)4516-4523
Number of pages8
Issue number32
StatePublished - Jul 22 2021


  • Cholera
  • Dose interval
  • Immunogenicity
  • Oral Cholera Vaccine
  • Zambia

ASJC Scopus subject areas

  • Molecular Medicine
  • Immunology and Microbiology(all)
  • veterinary(all)
  • Public Health, Environmental and Occupational Health
  • Infectious Diseases


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